Simulation and modelling study of a chemical absorption plant to evaluate capture effectiveness when treating high CO2 content iron and steel industry emissions

• Detailed results offer guidance for operation of systems cleaning high CO 2 flue gas. • Optimal L/G and solvent/CO 2 ratios predicted to be independent of gas flow rate. • Solvent loadings and capacity key to understanding optimal parameter relationships. • Column temperature profile assessment crucial to optimise system energy demand. • Developed simulation model can be calibrated to represent other MEA systems. Humanity must decarbonise to prevent climate disaster associated with CO 2 and other greenhouse gases. The iron and steel industry contribute significantly to global CO 2 , with 70 % of integrated steel plant emissions arising from the blast furnace. Green alternatives to blast furnaces are still in development, requiring an intermediate stepping-stone solution to begin the decarbonisation journey. Chemical absorption using amine solvents is a proven carbon capture technology, theoretically ideal for flue gas CO 2 concentrations and conditions typical of iron and steel making industrial processes. A representative simulation of the Translational Energy Research Centre (TERC) pilot-scale amine capture plant (ACP) was developed in Aspen Plus V11.0 and identified conditions to minimise the specific reboiler duty (SRD) for representative gases of the iron and steel industry. This work predicted operating conditions and trends when using a monoethanolamine (MEA) solvent concentration of 35 wt% across flue gas CO 2 concentrations up to 25 mol% CO 2 . This work established that optimal L/G and solvent/CO 2 ratios for MEA absorption systems can be predicted through knowledge of the flue gas CO 2 concentration and the desired capture efficiency of the system alone, without consideration of the volumetric gas flow rate of the system. For flue gas CO 2 concentrations of 10 to 25 mol%, optimal L/G ratios of 2.5 to 4.6 and solvent/CO 2 ratios of 17.1 to 13.5 were identified to achieve 90 % capture efficiency, with the optimal L/G ratio increasing by approximately 0.7 for each 5 mol% increase of CO 2 concentration. Optimal lean solvent loadings ranged from 0.245 to 0.294 mol·CO 2 /mol·MEA, with rich solvent loadings ranging from 0.500 to 0.517 mol·CO 2 /mol·MEA. Solvent capacities proved instrumental in understanding the relationship between optimal solvent flow rate and flue gas CO 2 concentration for different capture efficiencies. Temperature profile assessment of absorbing and stripping columns is crucial to optimise the system, as each column exhibits unique operational behaviours, with additional attention given to the cross-heat exchanger. The results illustrate key parameters and considerations for CO 2 capture of the iron and steel industry, providing initial setpoint conditions and guidance for optimisation. The developed simulation model can be calibrated to represent other MEA absorption systems.